1. Field of the Invention
The present invention relates to a rotor shaft which is supported by a deep groove ball bearing and a cylindrical roller bearing and which is used for an aircraft gas turbine and the like.
2. Description of the Related Art
FIG. 2 is an illustrative view of a conventional rotor shaft for use with an aircraft gas turbine and the like. The shaft is supported by a deep groove ball bearing and a cylindrical roller bearing. In FIG. 2, the rotor shaft is supported by three heavy load and high-speed rotation roller bearings. That is, at predetermined portions on the side of a joint of the rotor shaft 1 and on the side opposite thereto, there are respectively arranged cylindrical roller bearings 3 each of which has a large load bearing capacity with respect to a radial load and a coefficient of friction that is smaller than that of other type roller bearings and which is resistant against an impact load and is suitable for heavy-load and high-speed rotation of the rotor shaft. Also, at a predetermined portion on the side of the joint, there is arranged a single deep groove ball bearing 2 for bearing a thrust load applied on the rotor shaft 1 during its high-speed rotation.
As described above, the conventional rotor shaft 1 of an aircraft gas turbine engine and the like has a disadvantage in that, since the rotor shaft 1 is supported by the three bearings, the torque loss due to the bearings is extremely great and the rotor shaft is forced to become lengthy which results in giving rise to an adverse effect regarding weight reduction and the maintenance of rigidity of the rotor shaft thereby contributing to an increase in the manufacturing costs of the aircraft gas turbine and the like.